• Bulletin of the Korean Chemical Society
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• v.28 no.5
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• pp.805-810
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• 2007

Molecular recognition for a specific cation depending on the change of the oxidation state of the metal catalyst component contained in the hydrogel network has been studied in a self-oscillating hydrogel. The selfoscillating hydrogels are synthesized by the copolymerization of N-isopropylacrylamide (NIPAAm), lead methacrylic acid (Pb(MAA)2), and Ru(bpy)3 2+ monomer as a metal catalyst component. The recognition for a specific cation (in this study, Ca2+ has been used) is characterized by the adsorbed amount of Ca2+ into the gel. The recognition of the gels for Ca2+ is higher at the temperature below the LCST, and also higher at the oxidized state than at reduced state of the metal catalyst component which corresponds to a more swollen state. Moreover, a propagating wave induced by a periodic change of the oxidation state with the diffusion phenomena in the oscillating hydrogel shows a possibility for temporal and site-specific molecular recognition due to the local swelling of the gel.

• Bulletin of the Korean Chemical Society
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• v.30 no.6
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• pp.1401-1404
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• 2009

• Journal of Environmental Science International
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• v.17 no.12
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• pp.1373-1380
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• 2008

Anthracene appended new host compounds have been synthesized by imine reaction. Fluorescent open chain host compounds Trisanthryl-tris(2-aminoethyl)imine 1 was synthesized from the reaction of tris(2-aminoethyl)amine and anthracene-9-carboxaldehyde in EtOH. Tris-10-chloroanthryl-tris(2-aminoethyl)imine 2 was synthesized from tris(2-aminoethyl)amine and 10-chloro-9-anthraldehyde in EtOH. The structures of all reaction product were identified by $^1H$ NMR, $^{13}C$ NMR, GC/MS, FAB Mass, IR spectrum and DSC. Cation complexation behavior was investigated by fluorescence spectroscopy measurements. The capability of transition metals cation recognition between fluorescent open chain host compound 1, 2 were investigated with $Co^{2+},\;Ni^{2+}\;and\;Cu^{2+}$. The fluorescence intensity was increased by host compounds corresponding guest cations. The relative order of fluorescence intensity changes were $Co^{2+}>Cu^{2+}>Ni^{2+}$. Compound 2 is very sensitive fluorescent sensor of $Co^{2+}$ ion.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.453-456
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• 2010

The structural and energetic preferences of thiacalix[4]biscrown-5 with and without alkali metal ions ($Na^+$, $K^+$, $Rb^+$, and $Cs^+$) have been theoretically investigated for the first time using molecular dynamic (MD) simulations and density functional theory (MPWB1K/6-31G(d)//B3LYP/6-31G(d)) methods. The formation of the metal ion complex by the host is mainly driven by the electrostatic attraction between crown-5 oxygens and a cation together with the minor contribution of the cation-$\pi$ interaction between two facing phenyl rings around the cation. The computed binding energies and the atomic charge distribution analysis for the metal binding complexes indicate the selectivity toward a potassium ion. The theoretical results herein explain the experimentally observed extractability order by this host towards various alkali metal ions. The physical nature and the driving forces for cation recognition by this host are discussed in detail.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.305-308
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• 2002

선택적인 이온센서의 개발은 환경적, 생리학적, 의학적 중요성에 의해 높은 관심을 받고 있다. 지금까지 전기 화학적인 검출, 형광검출, 그리고 다른 광학적인 방법들에 근거한 매우 다양한 이온센서들이 연구되어 왔다. 금속이온들의 선택적인 결합은 음이온들이나 중성물질 보다 상당히 쉽게 결합하기 때문에, 금속이온 인식을 위한 형광 화학센서들의 개발이 일찍부터 이루어졌다. (중략)

• Journal of Photoscience
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• v.11 no.32
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• pp.83-87
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• 2004

A porphyrin compound containing a crown ether moiety (Por-Crown) and its zinc complex (ZnPor-Crown) have been prepared and the effect of the addition of alkali metal on their fluorescence has been investigated. As alkali metal cations were added, the absorption and fluorescence maxima did not change. However, the absorbance and intensity of fluorescence increased dramatically. Among the alkali metal cations tested, addition of K$^{+}$ and Cs$^{+}$ showed strongest enhancement of absorbance and fluorescence intensity of Por-Crown and ZnPor-Crown.own.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3625-3628
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• 2012

Fluorescent organic molecules that respond to changes in the $Fe^{2+}$ concentration with selectivity to other abundant di-valent metal ions will offer the ability to understand the dynamic fluctuations of the $Fe^{2+}$ ion in interesting media. The use of 6-Br-ppmbi, derived from 2-pyridin-2-yl-benzimidazole, for metal ion-selective fluorescence recognition was investigated. Screening of the main group and transition metal ions showed exclusive selectivity for $Fe^{2+}$ ions even in the presence of competing metal ions. In addition, the requirement for low concentrations of probe molecules to detect certain amounts of $Fe^{2+}$ ions make this sensor unique compared to previously reported $Fe^{2+}$ ion sensors.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.190-194
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• 2004

The structures and complexation energies of penta-O-tert-butyl ester 1 of p-tert-butylcalix[5]arene toward a series of alkyl ammonium guests have been optimized by ab initio HF/6-31G method. The calculated complexation efficiencies of 1 for alkyl ammonium guests have been found to be similar to the values of previously reported debutylated-calix[5]arene 2. Calculation results show that both of the calix[5]aryl derivatives have much better complexation ability toward ammonium cation without alkyl group over other alkyl ammonium guests. The structural characteristics of the calculated complexes are discussed as a function of the nature of the alkyl substituents of the ammonium guests.

• Bulletin of the Korean Chemical Society
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• v.22 no.11
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• pp.1248-1254
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• 2001

The conformations and energies of p-tert-butylcalix[4]crown-6-ether (1) and its alkyl ammonium complexes have been calculated by ab initio HF/6-31G quantum mechanics method. The cone conformation was found to be most stable for free host 1. We hav e determined the binding site of these host-guest complexes focusing on the crown-6-ether or p-tert-butylcalix[4]arene pocket of the cone conformation of host molecule 1. The primary binding site of host 1 for the recognition of alkyl ammonium guests was confirmed to be the central part of the crown moiety of cone conformation. The complexation energy calculations revealed that the ammonium cation without alkyl group showed the highest complexation efficiency when combined with host 1, that is in satisfactory agreement with the experimental results.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.197-203
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• 2001

A fusion protein, consisting of human epidermal growth factor as a recognition domain and human angiogenin as a toxin domain, can be used as a targeted therapeutic against breast cancer cells among others. The fusion protein was expressed as inclusion body in recombinant E. coli, and when the conventional, solution-phase refolding process was used the refolding yield was very low due to severe aggregation, probably due to the opposite surface charge due to vastly different pI values of each domain. Solid-phase refolding process exploiting ionic interactions between the solid matrix and the protein was tried, but the ionic binding yield was very low regardless of the resins and pH conditions used. To provide higher affinity toward the solid matrix, six lysine residues were tagged to the N -terminus of the hEGF domain When the cation exchange resins such as heparin- or CM-Sepharose were used as the matrix, the adsorption capacity increased 2.5-3 times and the subsequent refolding yield increased nearly IS times compared to the conventional process.